init

src/pricing/estimate.ts

@@ -0,0 +1,49 @@
+import type { ModelOffering } from '../t4t/lib/types';
+import { env } from '../env';
+
+const BPS_DIVISOR = 10_000n;
+const TOKENS_PER_MILLION = 1_000_000n;
+
+export interface ChatRequest {
+  model: string;
+  max_tokens?: number;
+  messages?: Array<{ content: string }>;
+}
+
+/**
+ * Rough upper-bound xBZZ cost for a single chat completion. Mirrors the
+ * `maxPayment` semantics on JobEscrow.postJob.
+ *
+ * Returns `{ raw, withMarkup }` so the caller can:
+ *   - post the *raw* amount on-chain as `maxPayment` (markup is operator
+ *     revenue, not paid to providers)
+ *   - reserve the *with-markup* amount off-chain
+ */
+export function estimateMaxXbzz(
+  req: ChatRequest,
+  offering: Pick<ModelOffering, 'inputPricePerMillionTokens' | 'outputPricePerMillionTokens' | 'maxContextTokens'>,
+): { rawWei: bigint; withMarkupWei: bigint } {
+  const maxInputTokens = estimateInputTokens(req);
+  const maxOutputTokens = BigInt(req.max_tokens ?? Number(offering.maxContextTokens));
+
+  const inputCost = (BigInt(maxInputTokens) * BigInt(offering.inputPricePerMillionTokens)) / TOKENS_PER_MILLION;
+  const outputCost = (maxOutputTokens * BigInt(offering.outputPricePerMillionTokens)) / TOKENS_PER_MILLION;
+  const rawWei = inputCost + outputCost;
+  const withMarkupWei = (rawWei * (BPS_DIVISOR + BigInt(env.MARKUP_BPS))) / BPS_DIVISOR;
+  return { rawWei, withMarkupWei };
+}
+
+/**
+ * Approximate input-token count from messages. Uses a 4-char-per-token
+ * heuristic — fine for an upper-bound estimate; the actual cost is recorded
+ * later from the JobClaimed event.
+ */
+function estimateInputTokens(req: ChatRequest): number {
+  const totalChars = (req.messages ?? []).reduce((acc, m) => acc + (m.content?.length ?? 0), 0);
+  return Math.ceil(totalChars / 4) + 16; // +16 for system / role overhead
+}
+
+/** Apply the same markup function used at reservation time to a settled cost. */
+export function applyMarkup(rawWei: bigint): bigint {
+  return (rawWei * (BPS_DIVISOR + BigInt(env.MARKUP_BPS))) / BPS_DIVISOR;
+}